The pretty red Coral, then, is really the hard part of a little jelly-animal.  This animal is much like a Sea-anemone, with a hard skeleton of lime.  Coral, as you know, looks like a solid rock; it is really made of needles of lime, fastened together into a solid mass by the little Coral Polyp.

Now, many of the Coral animals have the strange habit of budding.  The buds become perfect polyps, and then they, too, begin to bud.  In this way, those marvellous coral-reefs and coral-islands have been made.  Branch by branch, layer by layer, the hard Coral is built up by myriads of the small, soft-bodied creatures.  This kind of polyp can live only in warm, clear water.  So it is not found in the cold depths of the sea, nor in the seas near our islands, but in the warm shallow waters near tropical lands it flourishes so well that it builds up most wonderful Coral walls.  So strong are they that they can defy the terrific force of the waves.

[Illustration:  THE PICTURE STORY OF A CORAL ISLAND.]

Some coral-reefs are of immense size and strength.  One, near the coast of Australia, is nearly a thousand miles in length.  These marvellous works of the polyp are of great use, for they break the force of the waves, and so make a calm shelter for vessels.

The brilliant masses of Coral make a world of colour in the clear seas of the tropics, a gay garden inhabited by fishes of gaudy hues.  In dull seas we have, as a rule, dull creatures to match.  And in bright, warm, sunny seas the fishes are also brightly coloured.  A dull fish would show up amid such rich colours, so it is easy to know why Coral fish wear such fine clothes.

Many of them spend all their time among the Coral, their food being the living tips of the Coral “branches,” which they nip off with fine, sharp teeth.  Others have teeth like millstones, fit for crushing the hard Coral, and eating the fleshy body of the polyp within.

Blue, red and yellow, striped and spotted, and of wonderful shapes, are the fish which swim in these coloured gardens of the sea.  Some of them have golden bands round their bodies, and fine spines which wave in the water like shreds of weed—­all to help them hide in the bright, sunlit groves of Coral.

Gorgeous Sea-anemones of all shapes and sizes add to the brightness; and even the Shrimps, Prawns, and Crabs are coloured to fit their background.  Crabs are always surprising us with their queer ways and quaint “dresses”; and here, among the Coral, it is the same story.  For there are Crabs whose shelly coats are covered with coloured knobs and spikes, so that the sharpest eye cannot pick them out from the Corals on which they rest.

EXERCISES

1.  How does the Sponge obtain its food? 2.  What is Coral? 3.  How are Coral-reefs formed? 4.  Why are there no Coral-reefs in our seas?